Inkjet printing and energy-curable inks have experienced significant development over the last decade. In general, these developments have focused on more effective and efficient means to cure the ink after it has been deposited onto a substrate. The first energy-curable inkjet printing systems used medium pressure Mercury (vapor) bulbs. These bulbs were capable of producing a significant peak intensity (W/cm2) and doses of UV radiation (J/cm2) in a variety of wavelengths.
Several different approaches have been taken with respect to inkjet printing and radiation (e.g., ultraviolet) curing, including:                Initially printing a color layer on media, reversing the direction of the media, and then moving the media back to the start of the color layer. The print settings are then changed, and the color layer is overprinted with a layer of clear ink.        Initially printing a color layer on media, removing the media from the printing system, reinserting the media at the back of the printing system, and then overprinting the color layer with a layer of clear ink using different settings.        For flatbed printers, which are not suitable for printing on flexible media, either the rigid media or the print heads are fixed in place, and the un-fixed component (i.e., the media or the print heads) is moved on an X-Y table. These configurations allow printed areas of the media to be accessed again and a layer of clear ink to be overprinted on color layers.        
In each of the foregoing approaches to inkjet printing, there is a need to give the clear, radiation-curable ink sufficient time to level out before it is cured so that the gloss can be maximized.